Engine Controls - Tests W/codes - ECM Oldsmobile Toronado Trofeo

IPC SEGMENT CHECK

1. Turn ignition switch to the ON position. On non-CRT equipped vehicles, simultaneously push OFF and WARM buttons on the Electronic Climate Control Panel (ECCP). On CRT equipped vehicles, simultaneously push the OFF button and touch WARM key on the CRT monitor control panel (CRTM). (Scheme 154)
2. On both non-CRT and CRT monitor equipped vehicles, continue to depress OFF and WARM button/key until all segments and bulbs of the IPC, the Driver Information Center (DIC) panel and ECCP illuminate. (Scheme 155) When all segments are lit, system has entered self-diagnostic mode. Release OFF and WARM button/key.
3. Illuminating the segments of the IPC, DIC and ECCP ensures all display segments are working properly. If all segments illuminate, proceed to «DISPLAYING TROUBLE CODES»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__displaying-trouble-codes) in this article. Failure of any segment to illuminate may result in inaccurate test results. All inoperative segments of the display must be made to operate before proceeding with self-diagnostic procedures in this article.
4. Partial segment check is possible by depressing TEST button on IPC when vehicle is in Park or Neutral. Holding button depressed will light all vacuum fluorescent displays and all telltales on IPC in order to check for faulty bulbs or light panels.

Scheme 154

Scheme 155

EXIT SELF-DIAGNOSTICS

During self-diagnostic procedures, it is possible to exit service mode without erasing trouble codes. On non-CRT equipped vehicles, exit service mode by depressing BI-LEV button on the ECC panel and turning ignition switch to OFF position. On CRT monitor equipped vehicles, exit service mode by touching RTN key on the CRT monitor panel or exit by turning ignition switch to OFF position.

DISPLAYING TROUBLE CODES

1. The Electronic Control Module (ECM), Body Control Module (BCM), and Supplemental Inflatable Restraint (SIR) trouble codes automatically display after system enters self-diagnostics. ECM trouble codes are displayed first, followed by the BCM trouble codes and then SIR trouble codes.
2. All trouble codes appear in an ascending (3 digit) numerical order. ECM codes are prefixed with the letter "E", BCM Codes prefixed with the letter "B", and SIR codes prefixed with the letter "R".
3. In addition, all trouble codes are followed by the letter "C" or "H". Letter "C" stands for current and indicates a trouble code related fault presently exists. Letter "H" stands for history and indicates the system failure was not present the last time the code was accessed.
4. For example: code E016H is ECM trouble code number 016, set in response to a malfunction that occurred in the past (history). Code B410C is BCM trouble code number 410, set in response to a malfunction that is currently taking place.
5. If no ECM, BCM or SIR trouble codes are stored in memory, respectively, a NO E CODE, NO B CODE or NO R CODE message is displayed. Should the communication link between a component and the ECM or BCM fail, a NO ECM/BCM DATA message will be displayed.
6. Trouble code display can be by-passed at any time by pressing FAN DOWN button on EECP (Touch RTN key on CRT monitor).

ECM TROUBLE CODE IDENTIFICATION

ECM TROUBLE CODES

Note. To repeat trouble code display sequence, depress OFF button on ECC panel of NON-CRT equipped vehicles. On CRT equipped vehicles, touch LEVL key on the CRT monitor panel.

CLEARING TROUBLE CODES

See CLEAR CODES under TEST TYPE SELECTION .

MANUAL OPERATION OF SERVICE MODE

Note. Manual operation of service mode system is to be used with the TROUBLE CODE CHARTS section of this article. Prior to using flow charts, it will be necessary to become completely familiar with the procedures in MANUAL OPERATION OF SERVICE MODE.

SYSTEM SELECTION

1. After all trouble codes have been displayed (see «DISPLAYING TROUBLE CODES»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__displaying-trouble-codes) in this article), the "service mode" system can be directed to perform specific system diagnostic tests. Following the trouble code display, the first system available for testing will automatically be displayed. For example: ECM? may now be present on the display.
2. To select the desired system, (ECM, BCM, IPC, or SIR), advance and stop the DIC display as follows: On NON-CRT equipped vehicles, depressing the FAN DOWN button on the ECC panel will cycle the system selection list. When the desired diagnostic system is displayed, depress FAN UP button on ECC panel and the displayed system will be selected for testing.
3. On CRTM equipped vehicles, touching the NO key on the CRT monitor panel will cycle the system selection list. When the desired diagnostic system is displayed on the DIC display panel, touch the YES key on the CRT monitor panel and the displayed system will be selected for testing. (Scheme 154)

Note. To cancel a system selection and activate a repeat of the system selection process, depress the OFF button on the ECC panel of NON-CRT equipped vehicles. On CRTM equipped vehicles, touch the LEVL key on the CRT monitor panel.

TEST TYPE SELECTION

1. After the diagnostic system has been selected for testing, 6 test types are now made available for selection. The menu choices are: CLEAR CODES?, DATA?, INPUTS?, OUTPUTS?, OVERRIDE? and SNAPSHOT?. The DIC display may be showing any one of these 6 test type choices.
2. To advance the display, depress FAN DOWN button on the ECCP of NON-CRT equipped vehicles. On CRTM equipped vehicles, touch NO key on the CRT monitor panel.
3. When the desired test type is displayed, depress the FAN UP button on the ECCP (NON-CRT equipped). On CRTM equipped vehicles, touch YES key on the CRT monitor panel.

Note. To cancel a test type selection and activate a repeat of the test type selection process, depress the OFF button on ECC panel for NON-CRT equipped vehicles or for CRTM equipped vehicles, touch LEVL key on the CRT monitor panel. To exit diagnostics without clearing codes, depress the BI-LEVEL button on ECCP or touch RTN key on the CRT monitor panel.

The 6 test types are explained as follows

CLEAR CODES

Selection of CLEAR CODES? will result in the message CODES CLEAR or CODES NOT CLEAR being displayed, indicating whether the codes were successfully cleared. This message appears for 3 seconds, indicating all stored trouble codes have been erased from that system's memory. After 3 seconds, the display will automatically return to the next test type available for testing.

Note. After a trouble code has been cleared, a complete ignition cycle and possibly a test drive should be made, after which a recheck for the code should be made to ensure code did not reset.

DATA

Data test displays compare the malfunctioning system's present specifications with the specifications of a properly functioning system. DIC displays Data values.

INPUTS

1. Input test displays the voltage level of that circuit tested as HI or LO. Input test display is shown on DIC panel.
2. HI or LO refers to input terminal voltage for the particular circuit. The display also indicates if an input reading has changed since the test was selected. This feature permits technician to activate or deactivate any listed device/circuit and then return to the display to see if voltage reading has changed.
3. If a voltage reading change occurs, an X will appear next to the HI/LO indicator; otherwise a 0 will remain displayed indicating no change occurred. The X will only appear once per selected input. The HI/LO indicator will continue to change as the input changes.

OUTPUTS

Output test displays the voltage level of selected device/circuit as HI or LO. After three seconds, this level will cycle between HI and LO voltage. Output test display is shown on DIC panel.

OVERRIDE

Override test is represented as a percentage of the tested functions' full range during its current operation. This percentage value is displayed in the ECC panel's temperature display area (NON-CRT), or on CRT monitor panel's "service mode" screen. The display will alternate between the override percentage value ("--") and the normal operation value. This alternating display is a reminder that the tested function IS NOT being overridden.

Pressing WARM and COOL buttons simultaneously on ECCP (NON-CRT) begins override of function. Touching SLEW ,L and SLEW ,O keys simultaneously on CRT monitor panel begins override of function. Alternating display will stop, and show override value.

Pressing WARM button increases value, pressing COOL button decreases value (NON-CRT). Touching SLEW ,L key on CRT monitor panel increases value, touching SLEW,O key decreases value.

Normal program control is resumed in one of the following 3 ways

1. 1 - Selection of another override will cancel current override.
2. 2 - Selection of another system (ECM, BCM, IPC or SIR) will cancel current override.
3. 3 - Overriding the value beyond either extreme (0 or 90) will display "----" momentarily before resuming value. Releasing control button while "----" is displayed will resume normal program and display will start alternating.

Override test is unique in that while in override test, another test (i.e. DATA, INPUTS, or OUTPUTS) can be selected and be active at the same time with override test. After selecting override test, press the OFF button (NON-CRT equipped) or touch LEVL key (CRT equipped), to allow selection of another test type. ECC panel (or CRT monitor) will continue to display selected override. By pressing OFF and WARM or COOL buttons at same time (NON-CRT equipped), or by touching LEVL and SLEW keys at the same time (CRT equipped) it is possible to monitor effect of override on different parameters.

To exit diagnostics without clearing codes, depress the BI-LEV button on ECCP (NON-CRT) or touch RTN key on CRT monitor panel.

SNAPSHOT

Snapshot is a test type that will record all BCM or ECM data and inputs at one instant for review at a later time. Snapshot permits a technician triggered recording of specific current ECM/BCM data and input parameters for review at a later time. BCM and ECM have slightly different types of snapshot.

Note. Proceed to ECM SNAPSHOT or BCM SNAPSHOT (as applicable) after selecting snapshot test type.

EXPLANATION OF SPECIFIC TEST SELECTION

Following test type selection, the first of many specific tests will be made available for selection. The 4 characters of this display represent a test code. The first 2 characters of the test code are alphabetic letters which identify both the system and test type already selected. Study the following examples

1. If the BCM system and DATA test type were selected, BD will be the first 2 characters of the display. BD stands for BCM DATA. The last 2 characters numerically identify the specific test selection. For example: BD51 designates BCM DATA, test 51.
2. If the ECM system and Data test type were selected, ED will be the first 2 characters of the display. ED stands for ECM DATA. The numerals following these 2 characters will represent the particular specific test selection.
3. When BI appears as the first 2 characters of the test code, this signifies the BCM system and INPUT test type were selected. The last 2 characters numerically identify the specific test selection. For example: BI51 designates BCM INPUT, test 51.

MAKING SPECIFIC TEST SELECTION

1. On NON-CRT equipped vehicles, scrolling to a lower specific test number is done by depressing the FAN DOWN button. Scrolling to a higher specific test number is done by depressing the FAN UP button. The system will automatically display the value for whatever specific test number is displayed.
2. On CRT monitor equipped vehicles, scrolling to a lower specific test number is done by touching the NO key on the CRT monitor control panel. Scrolling to a higher number is done by touching the YES key. The system will automatically display the value for whatever specific test number is displayed.

Note. To cancel a specific test type selection and activate a repeat of the specific test type selection process, depress the OFF button on ECC panel of NON-CRT equipped vehicles or touch LEVL key on the CRT monitor control panel of CRT equipped vehicles.

Scheme 156

BCM SNAPSHOT (NON-CRT EQUIPPED VEHICLES)

Note. If directed here from TEST TYPE SELECTION under MANUAL OPERATION OF SELF-DIAGNOSTICS in this article, go to step 2).

1. SNAPSHOT allows the recall of system operating specifications present at the exact time a BCM malfunction code was set. Up to 3 snapshots may be recalled. In addition, one snapshot may be triggered on demand by depressing FAN UP button when DO B SNAP is displayed. To enter snapshot complete the following: Enter self-diagnostics. See «ENTERING SELF-DIAGNOSTICS»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm) . Display trouble codes stored in memory. See «DISPLAYING TROUBLE CODES»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__displaying-trouble-codes) . Select BCM system for testing. See «SYSTEM SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__system-selection) . Select SNAPSHOT test type. See «TEST TYPE SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__test-type-selection) . NOTE: To cancel snapshot test type selection and activate a repeat of the specific test type selection process, depress the OFF button on ECC panel.
2. Immediately following the selection of SNAPSHOT?, the system will display CODE BXXX SNAP SHOT. B stands for BCM. XXX is used here to represent the 3 digit trouble code stored in BCM snapshot.
3. With BXXX displayed, depressing the FAN DOWN button on the ECC panel will permit scrolling through the list of BCM diagnostic codes for which the BCM has stored a snapshot. See the article «TESTS W/CODES - BCM»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-bcm) . for list of BCM trouble codes which may be present in snapshot. NOTE: A trouble code displayed during the trouble code display cycle may NOT be present as a snapshot trouble code. If this is the case, exit SNAPSHOT by depressing the OFF button on the ECCP. This will return the display to the next available system selection.
4. After display of the last BCM trouble code for which a snapshot does exist, pressing the FAN DOWN button on the ECC will result in the DO B SNAP display.
5. Responding to this display by depressing the FAN DOWN button on the ECCP will return the display to the first BXXX SNAP? display. Responding to the DO B SNAP display by depressing the FAN UP button with SNAP DATA? or SNAP INPUTS? displayed, will select that test type for display.
6. At this point the display is controlled as it would be for non-snapshot data and inputs display; however, all values and status information represents memorized vehicle conditions. See «EXPLANATION OF SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__explanation-of-specific-test-selection) and «MAKING SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__making-specific-test-selection) .
7. Depressing the FAN UP key again with DO B SNAP? displayed will change DIC to display the SNAP DONE message to indicate new information has been stored in memory.

BCM SNAPSHOT (CRT EQUIPPED VEHICLES)

Note. If directed here from TEST TYPE SELECTION, go to step 2).

1. SNAPSHOT allows the recall of system operating specifications present at the exact time a BCM malfunction code was set. Up to 3 snapshots may be recalled. In addition, one snapshot may be triggered on demand by touching YES key when TAKE BCM SNAPSHOT is displayed. To enter snapshot complete the following: Enter self-diagnostics. See «ENTERING SELF-DIAGNOSTICS»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm) . Display trouble codes stored in memory. See «DISPLAYING TROUBLE CODES»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__displaying-trouble-codes) . Select BCM system for testing. See «SYSTEM SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__system-selection) . Select SNAPSHOT test type. See «TEST TYPE SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__test-type-selection) . NOTE: To cancel snapshot test type selection and activate a repeat of the specific test type selection process, touch the LEVL key on the CRT monitor.
2. Immediately following the selection of SNAPSHOT?, the system will display BXXX SNAPSHOT. "B" stands for BCM. XXX is used here to represent the 3 digit code stored in BCM snapshot.
3. With BXXX SNAPSHOT displayed, touching the NO key on the CRT monitor will permit scrolling through the list of BCM diagnostic codes for which the BCM has stored a snapshot. See the article «TESTS W/CODES - BCM»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-bcm) . under SELF-DIAGNOSTICS in this article for list of BCM trouble codes which may be present in snapshot. NOTE: A trouble code displayed during the trouble code display cycle may not be present as a snapshot trouble code. If this is the case, exit SNAPSHOT by touching the LEVL key on the CRT monitor. This will return the display to the next available system selection.
4. After display of the last BCM trouble code for which a snapshot does exist, touching the NO key on the CRT monitor will result in the TAKE BCM SNAPSHOT? display. Responding to this display by again touching the NO key will return the display to the first BXXX SNAPSHOT? display.
5. Responding to the TAKE BCM SNAPSHOT? display by touching the YES key on the CRT monitor with SNAP DATA? or SNAP INPUTS? displayed will select that test type.
6. At this point the display is controlled as it would be for non snapshot data and inputs displays; however all values and status information represent memorized vehicle conditions. See «EXPLANATION OF SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__explanation-of-specific-test-selection) and «MAKING SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__making-specific-test-selection) .
7. Touching the YES key again with TAKE BCM SNAPSHOT? displayed will change DIC to display the SNAP DONE message to indicate new information has been stored in memory.

ECM SNAPSHOT (NON-CRT EQUIPPED VEHICLES)

Note. If directed here from TEST TYPE SELECTION under MANUAL OPERATION OF SELF-DIAGNOSTICS in this article, go to step 2).

1. SNAPSHOT allows the recall of system operating specifications present at the exact time an ECM malfunction code was set. Up to 3 snapshots may be recalled. In addition, one snapshot may be triggered on demand. To enter snapshot, complete the following: Enter self-diagnostics. See «ENTERING SELF-DIAGNOSTICS»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm) . Display trouble codes stored in memory. See «DISPLAYING TROUBLE CODES»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__displaying-trouble-codes) . Select ECM system for testing. See «SYSTEM SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__system-selection) . Select SNAPSHOT test type. See «TEST TYPE SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__test-type-selection) . NOTE: To cancel snapshot test type selection and activate a repeat of the specific test type selection process, depress the OFF button on ECC panel.
2. Immediately following the selection of SNAPSHOT?, the system will display the message SNAP DONE. This message appears for 3 seconds to indicate all ECM data and inputs have been stored in memory. Following this 3 second information storage verification, the display will automatically proceed to the first available snapshot test type (i.e., SNAP DATA? or SNAP INPUTS?).
3. At this point, depressing the FAN DOWN button will display the next available snapshot test type. Display may be toggled between SNAP DATA? and SNAP INPUTS?.
4. Depressing the FAN UP button with SNAP DATA? or SNAP INPUTS? displayed will select that particular test type.
5. At this point, the display is controlled as it would be for non-snapshot data and inputs displays; however, all values and status information represents memorized vehicle conditions. See «EXPLANATION OF SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__explanation-of-specific-test-selection) and «MAKING SPECIFIC TEST SELECTION5»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__making-specific-test-selection) .
6. Depressing the FAN UP key with ECM SNAPSHOT? displayed will display the SNAPSHOT TAKEN message to indicate that new information has been stored in memory.

Scheme 157

ECM SNAPSHOT (CRT EQUIPPED VEHICLES)

Note. If directed here from TEST TYPE SELECTION, go to step 2).

1. SNAPSHOT allows the recall of system operating specifications present at the exact time an ECM malfunction code was set. Up to 3 snapshots may be recalled. In addition, one snapshot may be triggered on demand. To enter snapshot, complete the following: Enter self-diagnostics. See «ENTERING SELF-DIAGNOSTICS»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm) . Display trouble codes stored in memory. See «DISPLAYING TROUBLE CODES»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__displaying-trouble-codes) . Select BCM or ECM system (as desired) for testing. See «SYSTEM SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__system-selection) . Select SNAPSHOT test type. See «TEST TYPE SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__test-type-selection) . NOTE: To cancel snapshot test type selection and activate a repeat of the specific test type selection process, touch the LEVL key on the CRT monitor control panel.
2. Immediately following the selection of SNAPSHOT?, the system will display the message SNAP DONE. This message appears for 3 seconds to indicate all ECM data and inputs have been stored in memory. Following this 3 second information storage verification, the display will automatically proceed to the first available snapshot test type (i.e., SNAP DATA? or SNAP INPUTS?).
3. At this point, touching the NO key on the CRT monitor panel will display the next available snapshot test type. Display may be toggled between SNAP DATA? and SNAP INPUTS?.
4. Touching the YES key with SNAP DATA? or SNAP INPUTS? displayed will select that particular test type. From this point, the display is controlled as it would be for non-snapshot data and inputs displays; however, all values and status information represents memorized vehicle conditions. See «EXPLANATION OF SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__explanation-of-specific-test-selection) and «MAKING SPECIFIC TEST SELECTION»(/oldsmobile/toronado-trofeo/1990-1990/remont/testing-diagnostics/#engine-controls-tests-wcodes-ecm__making-specific-test-selection) .
5. Touching the YES key on the CRT monitor panel with ECM SNAPSHOT? displayed will display the SNAPSHOT TAKEN message to indicate that new information has been stored in memory.

STATUS LIGHT INDICATORS

During self-diagnostics, the status light display on ECC Panel or CRT monitor is used to indicate switchable parameter status. Each parameter status is indicated by its status light being turned ON or OFF. Status light indicators are relative to system level being tested (BCM or ECM). (Scheme 158)

The following are brief summaries of each systems status light indicators, starting with the ECM status light indicators

1. LOOP light (CRT equipped) or HIGH light (ECCP equipped) is ON when ECM is in closed loop fuel control. Light comes ON only after coolant and O2 sensors reach operating temperature.
2. TCC light (CRT equipped) or MED light (ECCP equipped) only indicates whether operation is enabled or disabled by ECM. Actual working operation depends on TCC system being in working order.
3. Oxy light (CRT equipped) or LOW light (ECCP equipped) stays ON when oxygen sensor signals rich exhaust condition to ECM. Light will flash ON and OFF during warm engine, steady throttle, and proper fuel mix condition.
4. EGR light (CRT equipped) or LOWER ARROW light (ECCP equipped) is ON when ECM is directing one of the 3 EGR solenoids to be ON. Light will be OFF if no EGR solenoids are ON as during idle condition.
5. 4th Gear light (CRT equipped) or OFF light (ECCP equipped) will be ON when ECM senses 4th gear pressure switch open. Light should only be on in 4th gear.
6. 3rd Gear light (CRT equipped) or AUTO light (ECCP equipped) will be ON when ECM senses 3th gear pressure switch open. Light should only be on in 3rd or 4th gear.
7. 2nd Gear light (CRT equipped) or "°C" light (ECCP equipped) will be ON when ECM senses 2nd gear pressure switch open. Light should only be on in 2nd, 3rd or 4th gear.
8. A/C Compressor Command UPPER ARROW (ECCP equipped) or COMP light (CRT equipped) will be ON only when ECM allows A/C clutch engagement through A/C relay. Light will also be ON if BCM requests ECM to turn clutch ON during test sequence. Light should be OFF if ECM commands disengagement.

The following are brief summaries of BCM system status light indicators

1. PRESS light (CRT equipped) or LOWER ARROW light (ECCP equipped) will be ON if BCM senses low refrigerant pressure switch is open. Light will remain OFF if A/C system is fully charged and operational. (However, light will come ON when outside vehicle ambient temperature is less than -5°F (-21°C), this is due to temperature-pressure relationship of R-12 refrigerant.)
2. OFF light (ECCP equipped) or REC light (CRT equipped) will be ON when BCM commands air recirculation.
3. MED light (ECCP equipped) or A/C light (CRT equipped) will be ON when BCM commands air flow out A/C vents. Light should also be ON in A/C and BI/LEVEL modes.
4. AIR UP light (CRT equipped) or LOW light (ECCP equipped) will be ON when BCM commands air flow out defroster outlets. Light should also be ON in defrost and A/C modes.
5. AIR DOWN light (CRT equipped) or HIGH light (ECCP equipped) will be ON when BCM commands air flow out floor outlets. Light should be ON in heater mode.
6. Left side AUTO light (ECCP equipped) or COMP light (CRT equipped) will be ON when BCM requests ECM to engage A/C compressor clutch.

Scheme 158

DATA DISPLAY CODE

Brief summary of each DATA parameter is as follows

ECM DATA PARAMETERS

1. ED01 Throttle position (TPS) displayed in percent from 0 to 100.
2. ED04 Coolant temperature (COOLANT TP) displayed in degrees Celsius (°C) from -40 to 151.
3. ED06 Injector pulse width (MS INJ PW) displayed in milliseconds (mS) from 0 to 100.2.
4. ED07 Oxygen sensor voltage (OXY SENSOR) displayed in volts from 0 to 1.14.
5. ED08 Spark advance (DEG SPARK) displayed in degrees from 0 to 70, similar to engine timing in degrees.
6. ED10 Battery voltage (BATT VOLTS) read in volts from 0 to 25.5.
7. ED11 Engine speed (RPM) displayed in RPM from 0 to 6375.
8. ED12 Vehicle speed (MPH) displayed in miles per hour from 0 to 159.
9. ED16 Knock retard (SPK ANGLE) displayed in degrees of timing pulled out from 0 to 45.
10. ED17 Knock sensor activity (OLD PA3) displayed as counts, an arbitrary number that increases from 0 to 9999 according to amount of activity from knock sensor.
11. ED18 Oxygen sensor cross counts (CROSS CTS) displayed as number of times O2 sensor crossed reference line each second.
12. ED19 Fuel integrator (INT FUEL) displayed in counts from 0 to 255.
13. ED20 Block learn multiplier (BLM FUEL) displayed in counts from 0 to 255.
14. ED21 Mass airflow (AIR FLOW) sensor displayed in grams per second of air flow from 0 to 255.
15. ED22 Idle air control (IAC MOTOR) displayed in steps of travel from 0 to 255.
16. ED23 Manifold air temperature (MAT) displayed in degrees (°C) from -40 to 152.
17. ED98 Ignition cycle counter (IGN CYCLES) value is number of times the ignition has been cycled to OFF since ECM trouble code was last detected. After 50 ignition cycles (key OFF, ON, OFF is one cycle) without any malfunctions being detected, all stored ECM codes are cleared.
18. ED99 ECM PROM ID (PROM ID) displayed as number up to four digits long which can bee used to identify MEM-CAL installed in ECM.

FOR CRT Control CODE

1. CD99 CRTC PROM I.D. (PROM ID) displayed as number up to four digits long, which can be used to verify that proper PROM was installed in the CRT monitor.

INPUT DISPLAY CODE DEFINITIONS

Brief summary of each systems INPUT parameters is as follows.

ECM INPUT PARAMETERS

1. EI71 Brake switch (BRK SW) display is LO when brake pedal is depressed.
2. EI74 Park-Neutral (PARK-NEUT) display is LO when vehicle is in Park or Neutral.
3. EI78 Power steering pressure switch (POWER STRG) display is LO when power steering pressure effort is high. Wheel is in cramp position.
4. EI79 Second gear switch (2ND GEAR) display is HI when vehicle is in 2nd gear.
5. EI80 Third gear switch (3RD GEAR) display is HI when vehicle is in 4th gear.
6. EI82 Fourth gear switch (4TH GEAR) display is HI when vehicle is in 4th gear.

OUTPUT DISPLAY CODE DEFINITIONS

Brief summary of each systems OUTPUT parameters is as follows.

ECM OUTPUT PARAMETERS

1. E000 CYCLE NONE will display and will not show HI or LO. This is normal resting code where no outputs will be cycled.
2. E001 TCC SOL display will be LO when TCC solenoid is ON (energized).
3. E004 EGR solenoid (EGR SOL #1) display will be LO when #1 EGR solenoid is ON (energized).
4. E005 EGR solenoid (EGR SOL #2) display will be LO when #2 EGR solenoid is ON (energized).
5. E006 EGR solenoid (EGR SOL #3) display will be LO WHEN #3 EGR solenoid is ON (energized).
6. E007 Canister purge solenoid (CAN PURG) display will be LO when solenoid is ON (energized).
7. E008 A/C RELAY display will be LO when A/C Clutch RELAY is ON (energized).
8. E009 No. 1 coolant fan relay (FAN REL 1) display is LO when coolant fan is ON (energized).
9. E010 No. 2 coolant fan relay (FAN REL 2) display is LO when coolant fan is ON (energized).
10. E011 IAC MOTOR output display will cycle LO (IAC extending) to HI (IAC retracting). DO NOT activate this output if IAC has been removed from throttle body.

OVERRIDE DISPLAY CODE DEFINITIONS

Brief summary of each OVERRIDE parameter is as follows.

Note. For CRT equipped vehicles, substitute SLEW 67,L and SLEW 67,O keys for WARM or COOL buttons in following parameters.

ECM OVERRIDE PARAMETERS

1. ES00 The NONE display will not show any value in display area on ECCP or CRT Monitor, as no overrides are active at this point. This is normal resting code where no overrides will be controlled. This code can be used to stop override control without having to go back to system selections.
2. ES01 TCC solenoid (TCC SOL) display will show commanded state of TCC solenoid ("00" not engaged, "99" - engaged). Pressing WARM button will engage TCC and pressing COOL button will disengage TCC. Vehicle must be in 3rd or 4th gear for override to operate.
3. ES02 EGR solenoid No. 1 (EGR SOL 1) can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
4. ES03 EGR solenoid No. 2 (EGR SOL 2) can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
5. ES04 EGR solenoid No. 3 (EGR SOL 3) can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
6. ES05 Canister purge solenoid (CAN PURG) can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
7. ES06 A/C RELAY can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
8. ES07 Cooling fan relay No. 1 (FAN REL 1) can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
9. ES08 Cooling fan relay No. 2 (FAN REL 2) can be turned OFF (00) by pressing COOL button or turned ON (99) by pressing WARM button.
10. ES09 IAC MOTOR display will show position IAC motor is being commanded to in percentage of travel. Vehicle must be in Park or Neutral. COOL button will retract motor (increasing RPM) and WARM button will extend motor (decreasing RPM).
11. ES10 Injector control override (INJECTOR) will work only when vehicle is in Park or Neutral. When entering override, display will show "0", all injectors will be working normally. WARM button will increment display by 1, up to 6 (or to 8, for V8 engine), and then return to "0". Display number indicates cylinder injector number that is being held off. Injector will continue to be held off until COOL button is used to turn injector back on. COOL button is used to toggle ON and OFF.

CHART A-1, NO SERVICE ENGINE SOON LIGHT

The SERVICE ENGINE SOON (SES) light is located in the IPC. Light is powered by Ignition 1, circuit No. 39 and ECM completes system ground to turn light ON. With ignition ON, engine not running, light should be ON. If with engine running light is ON steady, this indicates an ECM code is set. When system diagnostics are entered, light should flash, indicating service mode of ECM has been entered. The system monitor button does not affect SERVICE ENGINE SOON light.

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) This step splits circuit into 2 sections. SERVICE ENGINE SOON light illuminating after grounding ALDL terminal "D" indicates open is on ECM side of circuit. SERVICE ENGINE SOON light staying OFF would indicate fault is on IPC side of circuit.

Test Number 2) With test light, check circuit No. 39 to ensure voltage is available to SES light bulb. Check body ignition 1 fuse No. 14 if test light does not light.

Test Number 3) If test light DID NOT illuminate when connected between ECM terminal BA 6 and ground, ECM is not getting power. This is result of an open or short to ground (blown fuse) in circuit No. 439.

Test Number 4) This step checks for open in IPC or circuit No. 419. IPC terminal D2 is 12 volts. When test light connected between terminals D2 and C9 illuminates, it indicates that circuit No. 419 is complete through ALDL terminal D , which has been grounded.

Test Number 5) This step checks for open in ECM or circuit No. 419. If test light illuminates when backprobed to ECM harness terminal YC11 (Brown/White wire), fault is from poor contact at terminal YC11 or a faulty ECM.

Diagnostic Aids

An intermittent fault may be caused by poor connection, rubbed through wire insulation or wire broken inside insulation.

1. Check for poor connection at ECM terminal YC11 or IPC connector. Inspect wire harness connectors for backed out terminals, improper mating, broken connector locks, improperly formed or damaged terminals and poor terminal to wire crimp connection.
2. Inspect wire harness thoroughly for damage. A flickering test light indicates intermittent fault location.

Chart A-1: Circuit Diagram. Scheme 159

Chart A-1: Flow Chart No SES Light. Scheme 160

CHART A-2, SERVICE ENGINE SOON LIGHT WILL NOT GO OUT OR FLASH

The SERVICE ENGINE SOON (SES) light is located in the IPC. Light is powered by Ignition 1, circuit No. 39 and ECM completes system ground to turn light ON. With ignition ON, engine not running, light should be ON. If with engine running light is ON steady, this indicates an ECM code is set. When system diagnostics are entered, light should flash, indicating service mode of ECM has been entered. The system monitor button does not affect SERVICE ENGINE SOON light.

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) This step verifies SERVICE ENGINE SOON light remains ON with engine running and no ECM codes displayed.

Test Number 2) Disconnecting ECM harness Yellow connector determines if short to ground is in ECM or elsewhere in circuit. If SERVICE ENGINE SOON light remains ON, fault is not in ECM.

Test Number 3) Check for short to ground in the IPC or in circuit No. 419. If test light illuminates when connected between IPC harness connector terminals C9 and D2, fault is a short to ground in circuit No. 419.

An intermittent fault may be caused by poor connection, rubbed through wire insulation or wire broken inside insulation.

1. Check for poor connection at ECM terminal YC11 or IPC connector. Inspect wire harness connectors for backed out terminals, improper mating, broken connector locks, improperly formed or damaged terminals and poor terminal to wire crimp connection.
2. Inspect wire harness thoroughly for damage. A flickering test light indicates intermittent fault location.

Chart A-2: Flow Chart No SES Light Will Not Go Out Or Flash. Scheme 161

CODE E013, OPEN OXYGEN SENSOR CIRCUIT

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Code E013 will set under the following conditions

1. Codes E021 or E022 not set
2. Engine at normal operating temperature
3. Engine run time greater than 40 seconds
4. O2 signal voltage ED07 display, steady between .35 and .55 volt
5. Throttle position sensor greater than .55 volt
6. All conditions must be met for about 30 seconds

If the above conditions for a Code E013 exist, the system will not go to closed loop.

Test Number 2) This will determine if the sensor or the wiring is the cause of the Code E013.

Test Number 3) In performing this test, use only a high impedance digital volt/ohmmeter. This test checks the continuity of circuits No. 412 and 413. If circuit No. 413 is open, the ECM voltage on circuit No. 412 will be greater than .6 volt (600 mV).

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, observe ED15 display, O2 sensor voltage while moving related connectors and wiring harness, with warm engine running at part throttle in closed loop. If the failure is induced, the O2 sensor voltage reading will change from its normal fluctuating voltage (greater than .60 volt and less than .30 volt) to a fixed value around .45 volt. This may isolate the location of malfunction.

Code E013: Circuit Diagram & Flow Chart O2 Sensor Circuit. Scheme 162

CODE E014, COOLANT SENSOR TEMPERATURE TOO HIGH

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Code E014 will set if signal voltage indicates a coolant temperature greater than 282°F (130°C) for .4 second.

Test Number 2) This test will determine if circuit No. 410 is shorted to ground which will cause the conditions for Code E014. If Code E014 is set, the ECM will use 119°F (48.6°C) for fuel control.

Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect ECM harness connectors for backed out terminal YD4, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, observe ED04 display (coolant temperature) while moving related connectors and wiring harness. If the failure is induced, the coolant temperature display will change. This may help to isolate location of malfunction.
3. Shifted Sensor. The temperature-to-resistance value scale may be used to test the coolant sensor at various temperature levels to evaluate the possibility of a shifted (mis-scaled) sensor, which may result in driveability complaints.

Code E014: Circuit Diagram. Scheme 163

Code E014: Flow Chart Coolant Sensor Temp Too High. Scheme 164

CODE E015, COOLANT SENSOR TEMPERATURE TOO LOW

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Code E015 will set if signal voltage indicates a coolant temperature less than -40°F (-40°C) for at least 2 seconds.

Test Number 2) This test simulates a Code E014. If the ECM recognizes the low signal voltage (high temperature), and the CTS display reads 130°C, the ECM and wiring are okay.

Test Number 3) This test will determine if circuit No. 410 is open. There should be 5 volts present at sensor connector if measured with a digital volt/ohmmeter. If Code E015 is set, the ECM will use 119°F (48.6°C) for fuel control.

Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect ECM harness connectors for backed out terminal YD4, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, observe ED04 display (coolant temperature) while moving related connectors and wiring harness. If the failure is induced, the coolant temperature display will change. This may help to isolate location of malfunction.
3. Shifted Sensor. The temperature-to-resistance value scale may be used to test the coolant sensor at various temperature levels to evaluate the possibility of a shifted (mis-scaled) sensor, which may result in driveability complaints.

A faulty connection, or an open in circuits No. 410 or 452 will result in a Code E015. If Code E023 is also set, check circuit No. 452 for faulty wiring or connections. Check terminals at sensor for good contact.

Code E015: Flow Chart Coolant Sensor Temp Too Low. Scheme 165

CODE E016, BATTERY VOLTAGE TOO HIGH

The ECM monitors battery or system voltage on circuit No. 480 to terminals BB1 and BC16. If ECM detects voltage greater than 16 volts, it will turn the SERVICE ENGINE SOON light on and set a Code E016 in memory.

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Test generator output to determine proper operation of voltage regulator. Run engine at moderate speed and measure voltage across battery. If greater than 16 volts, repair generator.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect harness connectors for backed out terminals BC16 or BB1, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, observe ED10 display, while moving related connectors. If the failure is induced, the battery voltage will abruptly change. This may help to isolate the location of the malfunction. An engine stall while manipulating the harness indicates that the ECM has lost voltage at terminal BC16 or BB1. Check for loose connectors in circuit No. 480.

Note. Charging battery with a battery charger and starting the engine may set a Code E016.

Code E016: Circuit Diagram. Scheme 166

Code E016: Flow Chart Battery Voltage Too High. Scheme 167

CODE E021, TPS SIGNAL VOLTAGE HIGH

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Code E021 will set under the following conditions occur

1. Engine is running and airflow is less than 15 gm/sec
2. TPS signal voltage is greater than 2.5 volts
3. Code E033 or E034 not present at first start up
4. All conditions met for 5 seconds

With closed throttle, ignition on or engine at idle, voltage at terminal 3D13 should be .34-.46 volt. If not, TPS should be adjusted to specification.

Test Number 2) With TPS unplugged, TPS voltage should go low and Code E022 will set, if ECM and wiring are okay.

Test Number 3) Probing circuit No. 452 with a test light checks sensor ground circuit. A faulty sensor ground circuit will cause a Code E021.

An ED01 display reads throttle position in volts. With closed throttle, ignition on or at idle, voltage should be .34-.46 volt. If not, adjust TPS to specification. An open in circuit No. 452 will result in a Code E021. Check for the following conditions

1. Poor Connections or Damaged Harness. Inspect ECM harness connectors for backed out terminal YD13, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connections and damaged harness.
2. Intermittent Test. If connections and harness check out okay, monitor TPS voltage on ED01 display while moving related connectors and wiring harness. If failure is induced, coolant temperature display will change. This may help to isolate location of malfunction.
3. TPS Scaling. Observe TPS voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TPS voltage when throttle was closed, to greater than 4 volts when throttle is held at WOT position.

Code E021: Flow Chart TPS Signal Voltage High. Scheme 168

CODE E022, TPS SIGNAL VOLTAGE LOW

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) Code E022 will set if engine is running and TPS signal voltage is less than .2 volt for 4 seconds.

Test Number 2) Simulates Code E021. If ECM recognizes high signal voltage, ECM and wiring are okay.

Test Number 3) With closed throttle, ignition on or engine at idle, voltage at terminal YD13 should be .34-.46 volt. If voltage is not okay, check TPS adjustment.

Test Number 4) Simulates a high signal voltage. Checks circuit No. 417 for open.

The ED01 display reads throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward WOT. An open or short to ground in circuit No. 416 or 417 will result in a Code E022. Check for the following conditions

1. Poor Connections. Inspect ECM harness connectors for backed out terminal YD13, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness.
2. Intermittent Test. If connections and harness checks out okay, monitor TPS voltage while moving related connectors and wiring harness. If failure is induced, coolant temperature display will change. This may help to isolate location of malfunction.
3. TPS Scaling. Observe TPS voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TPS voltage when throttle was closed, to greater than 4 volts when throttle is held wide open.

Code E022: Flow Chart TPS Signal Voltage Low. Scheme 169

CODE E023, MAT SENSOR SIGNAL VOLTAGE HIGH

Note. Test numbers refer to test numbers on diagnostic chart.

Code E023 will set if a signal voltage indicates a manifold air temperature less than -40°F (-40°C) for 4 seconds. Due to the conditions necessary to set a Code E023, the Service Engine Soon (SES) light will stay only while fault is present.

Test Number 1) The ED23 display may not be used to diagnose this fault, due to the ECM transmitting default values. A Code E023 will set, due to an open sensor, wire or connection. This test determines if wiring and ECM are okay.

Test Number 2) If resistance is greater than 25,000 ohms, inspect air cleaner for ice. If ice is not present, replace sensor. If fault is intermittent, see INTERMITTENTS in H - TESTING W/O CODES article.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect harness connectors for backed out terminals BA5, YD11, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, observe ED23 display while moving related connectors and wiring harness with warm engine running at part throttle in closed loop. If the failure is induced, the MAT display may change the 40°C default value to the proper ambient temperature reading. This may help to isolate location of the malfunction.

Code E023: Flow Chart MAT Sensor Signal Voltage High. Scheme 170

CODE E024, VEHICLE SPEED SENSOR (VSS) CIRCUIT

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Code E024 will set if vehicle speed signal is less than 3 MPH when the following conditions exist

1. Engine is running
2. No Code E029 or E031
3. Vehicle is in 4th gear
4. Above conditions met for 40 seconds

The PM generator only produces a signal if drive wheels are turning greater than 3 MPH.

Test Number 2) Before replacing ECM, check MEM-CAL for correct application.

The on-board diagnostic display should indicate a vehicle speed whenever the drive wheels are turning greater than 3 MPH. Check circuits No. 400 and 401 for proper connections to ensure they are clean and tight.

Code E024: Circuit Diagram & Flow Chart VSS Circuit. Scheme 171

CODE E025, MAT SENSOR CIRCUIT HIGH TEMP INDICATED

Note. Test numbers refer to test numbers on diagnostic chart.

Code E025 will set if

1. Signal voltage indicates manifold air temperature greater than 275°F (135°C)
2. A vehicle speed is present
3. Both of the above requirements are met for at least 16 seconds

Due to the conditions necessary to set a Code E025, SERVICE ENGINE SOON light will only stay on while fault is present.

Test Number 1) If Code E025 is current, ED23 display may be used to diagnose this fault. If the fault is current, ECM will transmit 148°C as the data value. If fault is intermittent, see INTERMITTENTS in H - TESTING W/O CODES article.

Code E025: Flow Chart MAT Sensor Circuit (High Temp Indicated). Scheme 172

CODE E026, QUAD-DRIVER (QDM) ERROR

The ECM is used to control several components such as those illustrated in the mini circuit schematic. ECM controls these devices through the use of a Quad-Driver module (QDM). When the ECM is commanding a component on, the voltage potential of the output circuit will be low (near zero volts). When the ECM is commanding the output circuit to a component off, the voltage potential of the circuit will be high (near battery voltage). The primary function of the QDM is to supply the ground for the component being controlled.

Each QDM has a fault line which is monitored by the ECM. The fault line signal is available on the data stream for Scan tester equipment. The ECM will compare the voltage at the QDM based on accepted values of fault line. If the QDM fault detection circuit senses a voltage other than the accepted value, the fault line will go from a low signal on the data stream, to a high signal and a Code E026 will set if applicable.

Some QDM circuits will switch from low to high normally. Examples: QDM No. 2, if A/C pressure switch closes and turns on high speed coolant fan or QDM No. 3, if brake is depressed. These conditions are normal and no Code E026 is set. These are accepted conditions. A fault on QDM No. 2 will not set a Code E026, but diagnosis may be done by ensuring A/C is turned off. Some Scan tools will cause a false Code E026 to set if engine is running and service brake is depressed for over 30 seconds.

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) The ECM does not know which controlled circuit caused the Code E026. This chart will go through each of the circuits to determine which is at fault. This test also checks SERVICE ENGINE SOON light driver and SERVICE ENGINE SOON light circuit.

Test Number 2) QDM fault symptoms

1. TCC inoperative, Code E039
2. EGR inoperative, Codes E063, E064 and E065
3. Coolant fan on low speed all the time or won't come on at all
4. Poor driveability due to 100 percent canister purge

Test Number 3) This test will determine which circuit is out of specification. All circuits, except YC11, SERVICE ENGINE SOON light, YC9, and hot light, should have battery voltage when key is on, engine not running. Diagnostic test terminal is not grounded Terminal BB1 is ECM ground.

Test Number 4) This test will determine if problem is the circuit or the component. As factory installed ECM is protected with an internal fuse, it is highly unlikely that ECM needs replacement.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following condition

1. Inspect ECM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Code E026: Circuit Diagram & Flow Chart Quad-Driver (QDM) Error (1 of 3). Scheme 173

Code E026: Flow Chart Quad-Driver (QDM) Error (2 of 3). Scheme 174

Code E026: Flow Chart Quad-Driver (QDM) Error (3 of 3). Scheme 175

CODES E027, E028 & E029, 2ND, 3RD & 4TH GEAR SWITCH DIAG

Gear switches are located inside the transaxle. They are pressure operated switches that are normally closed. The ECM supplies 12 volts through each selected circuit to switch. In any condition other than the specific gear application, signal line monitors low voltage or low potential. As road speed increases, hydraulic pressure is applied to specific gear clutches, and gear switch opens. During this time, ECM monitors high 12-volt potential and interprets this to indicate that gear is applied. The ECM uses gear signals to control fuel delivery (and TCC).

Note. Test numbers refer to test numbers on diagnostic chart.

Code E027 will set under the following conditions

1. Circuit No. 581 indicates ground or closed switch when vehicle is in 4th gear operation
2. Code E029 not present
3. Circuit No. 446 is open when engine is first started
4. Circuit No. 581 indicates ground or closed switch when vehicle is in 4th gear operation
5. Circuit No. 581 indicates an open (Drive) when the engine is first started

Code E028 will set under the following conditions

1. Circuit No. 108 indicates ground or closed switch when vehicle is in 4th gear operation
2. Circuit No. 108 indicates an open (Drive) when the engine is first started
3. Circuit No. 446 is open when engine is first started

Code E029 will set under the following conditions

1. Circuit No. 446 indicates ground or closed switch when vehicle is in 4th gear operation.
2. Circuit No. 446 indicates an open (Drive) when the engine is first started.

Test Number 1) DVOM must be used. A test light will not light due to very low current being supplied by ECM.

Test Number 2) Checks to see if circuit is grounded through switch.

Test Number 3) Checks for a good, properly operating switch. Also checks circuit within transaxle for an improper ground.

An intermittent may be caused by a poor connection, incorrectly routed harness, rubbed through wire insulation or a wire broken inside insulation. Check for the following

1. Poor Connection at ECM pins. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal to wire connection.
2. Misrouted Harness. Inspect wiring harness to ensure that it is not too close to high voltage wires, such as spark plug leads.
3. Damaged Harness. Inspect harness for damage. If harness appears okay, observe EI79, EI80 and EI82 displays while moving related connectors and wiring harness. A change in display would indicate the intermittent fault location.

Codes E027, 28 & 29: Circuit Diagram. Scheme 176

Codes E027, 28 & 29: Flow Chart Trans Gear Shift Diagnosis. Scheme 177

CODE E031, PARK/NEUTRAL SWITCH CIRCUIT

The Park/Neutral (P/N) switch contacts are part of the neutral start switch and are closed to ground in Park or Neutral, and open in Drive. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when the voltage on circuit No. 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to determine control of idle air control, EGR and VSS.

Code 31 will set under the following conditions

1. If circuit No. 434 indicates P/N (grounded) while in Drive range and 4th gear TCC engaged, EGR would be inoperative, resulting in possible detonation.
2. If circuit No. 434 indicates Drive (open) at start up, a drop in idle may exist when gear selector is moved into Drive range.
3. If transaxle 4th gear switch has an intermittent open, ECM thinks vehicle is in 4th gear and will set Code E031.

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) Checks for a switch closed to ground in Park position.

Test Number 2) Checks for an open switch in Drive range.

Test Number 3) Ensure that on-board diagnostics EI74 indicates Drive (HI), even while wiggling shifter. This will test for an intermittent or misadjusted switch in Drive or Overdrive range.

Code E031: Flow Chart Park/Neutral Switch Circuit. Scheme 178

CODE E034, MASS AIRFLOW SENSOR CIRCUIT

The Mass Airflow (MAF) sensor measures the flow of air which passes through it in a given time. The ECM uses this information to monitor the operating condition of the engine for fuel delivery calculations. A large quantity of air movement indicates acceleration, while a small quantity indicates deceleration or idle. The MAF sensor produces a frequency signal, which cannot be easily measured. The sensor can be diagnosed using the procedures in this chart. Code E034 will set, when either of the following sets of conditions exists

1. Engine running.
2. No MAF sensor signal for 250 milliseconds
3. Above conditions for greater than 4 seconds

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) This step checks to see if ECM recognizes a problem.

Test Number 2) A voltage reading at sensor harness connector terminal A of less than 4 volts, or greater than 6 volts, indicates a fault in circuit No. 492 or poor connections.

Test Number 3) Verifies that both ignition voltage and a good ground circuit are available.

Check for the following

1. Poor Connection at ECM pin YD10. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal to wire connection.
2. Misrouted Harness. Inspect MAF sensor harness to ensure that it is not too close to high voltage wires, such as spark plug leads.
3. Damaged Harness. Inspect harness for damage. If harness appears okay, observe ED21 display while moving related connectors and wiring harness. A change in display would indicate the intermittent fault location.
4. Plugged Air Intake Filter. A WOT acceleration from a stop should cause MAF reading (ED21) to range from about 4.7 at idle, to 100 or greater at the time of 1-2 transmission shift. If not, check for air intake restriction.

Code E034: Circuit Diagram & Flow Chart Mass Airflow Sensor Circuit. Scheme 179

CODE E038, BRAKE SWITCH CIRCUIT

The ECM monitors the status of brake switch circuits through ECM terminal BC4. Code E038 will set under the following conditions

1. Code E024 is not present.
2. Vehicle speed has been greater than 35 MPH and back to zero MPH several times
3. Status of circuit No. 420 has not changed state high to low

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) This step checks for battery voltage available for circuit No. 420.

2) Checks fuse, switch and circuit for battery voltage.

Code E038: Circuit Diagram. Scheme 180

Code E038: Flow Chart Brake Switch Circuit. Scheme 181

CODE E039, TORQUE CONVERTER CLUTCH (TCC) CIRCUIT

The ECM controls TCC operation by grounding circuit No. 422 through the QDM. Code E039 will set under the following conditions

1. Code E029 is not present
2. Brake switch is closed (off)
3. TCC is commanded on by ECM
4. Vehicle is in 4th gear
5. The engine speed to vehicle speed ratio is outside of its window of operation
6. All of the above for a time greater than 30 seconds

Note. Test numbers refer to numbers on diagnostic chart.

Test Number 1) Checks availability of battery voltage on circuit No. 420.

Test Number 2) Check fuse, brake switch and battery voltage circuit to the TCC solenoid.

Codes E026 and E038 in combination with a Code E039, would indicate a problem with fuse, circuit No. 639, brake switch or wire ahead of splice. A single Code E038 is the result of a wire or circuit No. 420 problem between the splice and the ECM, poor connection to ECM connector, or possibly the ECM. A Code E026 with an Code E039 is the result of a problem in circuit from splice to ECM. Another cause might be an open or grounded circuit No. 420 ahead of TCC solenoid, a bad TCC solenoid, open or grounded circuit No. 422, bad connections at ECM connector YC10 or ECM.

Code E039: Flow Chart TCC Circuit. Scheme 182

Quick reference

1. (Scheme 184)for Code E041 flow chart.
2. (Scheme 183)for Code E041 supplemental wiring.

All Updated Information

All the Code E041 information here (including the flow chart) has been updated as per the General Motors Technical Service Bulletin (TSB) listed below. All outdated information has been discarded.

1. Buick 90-8-22

Circuit Description

During cranking, the ignition module monitors the dual crank sensor sync signal. The sync signal is used to determine the correct cylinder pair to spark first.

After the sync signal has been processed by the ignition module, it sends a fuel control reference pulse to the ECM. When the ECM receives this pulse it will command all six injectors to open for one priming shot of fuel in all cylinders.

After the priming, the injectors are left off for the next six fuel control reference pulses from the ignition module (two crankshaft revolutions). This allows each cylinder a chance to use the fuel from the priming shot.

During this waiting period, a cam pulse will have been received by the ECM. Now the ECM begins to operate the injectors sequentially based on true camshaft position.

However, if the cam signal is not present at start-up, a Code E041 will set and the ECM will start sequential fuel delivery in random pattern with a 1 in 6 chance that fuel delivery is correct.

Test Description

The numbers below refer to the circled numbers in the diagnostic flow chart.

Test Number 1) This step verifies proper operation of circuits 633, 644, and 645. (Scheme 183)for circuit identification.

Test Number 2) Step validates the integrity of Circuit 630 from the ignition module to the ECM. (Scheme 184)for circuit identification.

Test Number 3) If the camshaft gear magnet is interfacing with the cam sensor the voltage reading will be zero, bumping engine will cause the condition to go away.

Test Number 4) If the voltage reading of terminal "BC5" is constantly varying and connection to terminal "BC5" are good, the ECM is faulty.

An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside the insulation.

Check for the following

1. Poor Connection or Damaged Harness: Inspect ECM harness connectors for backed out terminal "BC5", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test: If connections and harness check okay, monitor a digital voltmeter connected from ECM terminal "BC5" to ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.

Scheme 183

Scheme 184

CODE E042, EST IGNITION CIRCUIT

The C(3)I module sends a reference signal to the ECM when the engine is cranking. When the engine is running less than 400 RPM, the C(3)I module controls ignition timing. When the engine speed exceeds 400 RPM, the ECM sends a 5 volt signal on by-pass circuit No. 424 to switch timing to ECM control. An open or ground in the EST circuit will stall the engine and set a Code E042. The engine can be restarted but will run on module timing. The following conditions must be met to set a Code E042

1. Engine speed greater than 600 RPM with no EST pulse for 200 milliseconds (open or grounded circuit No. 423)
2. ECM commanding by-pass mode (open or grounded circuit No. 424)

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) Checks to see if ECM recognizes a problem. If it does not set Code E042, it is an intermittent problem and could be due to a loose connection.

Test Number 2) With ECM disconnected, ohmmeter should be reading less than 200 ohms, which is the normal resistance of EST circuit through C(3)I module. A higher resistance would indicate a fault in circuit No. 423, poor C(3)I module connection, or faulty C(3)I module.

Test Number 3) If test light was on when connected from 12 volts to ECM harness terminal BC7, either circuit No. 424 is shorted to ground or C(3)I module is faulty.

Test Number 4) Checks to see if ignition module switches when by-pass circuit is energized by 12 volts through test light. If ignition module actually switches, ohmmeter reading should shift to greater than 6000 ohms.

Test Number 5) Unplugging ignition module should cause ohmmeter to read as if it were monitoring an open circuit (infinite reading). If not, circuit No. 423 is shorted to ground.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect ECM harness connectors for backed out terminals BC7 or BC8, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, connect digital voltmeter from affected terminal to ground and move related connectors and wiring harness. If failure is induced, voltage reading will change.

Code E042: Circuit Diagram. Scheme 185

Code E042: Flow Chart EST Ignition Circuit. Scheme 186

CODE E043, ELECTRONIC SPARK CONTROL (ESC) CIRCUIT

The knock sensor is used to detect engine detonation. The ECM will retard electronic spark timing based on the signal being received. The circuitry within the knock sensor causes the ECM's supplied 5-volt signal to be pulled down, so that under a no knock condition, circuit No. 496 would measure about 2.5 volts. The knock sensor produces an AC signal which rides on the 2.5 volts (DC voltage). The amplitude and signal frequency are dependent upon the knock level.

If circuit No. 496 becomes open or shorted to ground, voltage will either go greater than 3.5 volts or less than 1.5 volts. If either of these conditions are met for about 5 seconds, a Code E043 will stored.

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) Code E043 will set if

1. Voltage on circuit No. 496 goes greater than 3.5 volts or less than 1.5 volts
2. All of above conditions met for 5 seconds

If an audible knock is heard from the engine, repair internal engine problem. Normally, no knock should be detected at idle.

Test Number 2) If tapping on engine lift hook does not produce a knock signal, try tapping engine closer to sensor before proceeding.

Test Number 3) The ECM supplies 5 volts through a pull-up resistor. A reading of 4-6 volts should be present at knock sensor terminal.

Test Number 4) This test determines if knock sensor is faulty or if ESC portion of the MEM-CAL is faulty.

Check circuit No. 496 for a potential open or short to ground. Also check for proper installation of MEM-CAL.

Code E043: Circuit Diagram & Flow Chart ESC Circuit. Scheme 187

CODE E044, OXYGEN SENSOR CIRCUIT (LEAN EXHAUST INDICATED)

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) Running the engine at 1000 RPM keeps O2 sensor hot, so an accurate display voltage is maintained.

Test Number 2) Opening O2 sensor wire should result in a voltage display of between 350 and 550 mV. If display is still fixed less than 350 mV, fault is a short to ground in circuit No. 412 or ECM is faulty.

Using ED20 display, observe the block learn values at different RPM and airflow conditions. If the conditions for Code E044 exists, the block learn values will be around 150. Check for the following conditions

1. Oxygen sensor pigtail may be mispositioned and contacting exhaust manifold.
2. Check for intermittent ground in wire between connector and sensor.
3. A Mass Airflow (MAF) sensor output that causes ECM to sense a lower than normal airflow will cause the system to go lean. Disconnect MAF sensor and if lean condition is eliminated, replace MAF sensor.
4. Perform injector balance test. See I - SYSTEMS/COMP TESTS article.
5. Water, even in small amounts, near in-tank fuel pump inlet can be delivered to injectors. Water causes a lean exhaust and can set Code E044.
6. System will be lean if pressure is too low. It may be necessary to monitor fuel pressure while driving vehicle at various road speeds and/or loads to confirm problem.
7. If there is an exhaust leak, engine can cause outside air to be pulled into exhaust, across the oxygen sensor. Vacuum or crankcase leaks can cause a lean condition.
8. If all of the above checks are okay, replace oxygen sensor.

Code E044: Circuit Diagram & Flow Chart O2 Circuit (Lean Exhaust Indicated). Scheme 188

Using ED20 display, observe the block learn values at different RPM and airflow conditions. If the conditions for Code E045 exists, the block learn values will be around 115. Check for the following conditions

1. Fuel Pressure. System will go rich if pressure is too high. ECM can compensate for some increase in fuel pressure. If fuel pressure becomes too high, a Code E045 may be set.
2. Rich Injector. Perform injector balance test, see SYSTEM/COMPONENT TESTS article.
3. Leaking Injector. See SYSTEM/COMPONENT TESTS article.
4. Canister Purge. Check for fuel saturation. If full of fuel, check canister control and hoses.
5. MAF Sensor. An output that causes ECM to sense a higher than normal air flow can cause system to go rich. Unplugging MAF sensor will allow ECM to set a fixed value for sensor. Substitute a different MAF sensor if rich condition is rectified while sensor is unplugged.
6. Fuel. Check for leaking fuel pressure regulator diaphragm by checking vacuum line to regulator for raw fuel. Check for contaminated fuel.
7. TPS. An intermittent TPS output will cause system to go rich, due to a false indication of engine acceleration.
8. EGR. An EGR staying open (especially at idle) will cause the O2 sensor to indicate a rich exhaust, and could result in a Code E045.

Code E045: Circuit Diagram & Flow Chart O2 Circuit (Rich Exhaust Indicated). Scheme 189

CODE E046, POWER STEERING PRESSURE SWITCH CIRCUIT

To set a Code E046, the following conditions must be met

1. Closed power steering switch. EI78 indicates LO (low voltage potential)
2. Vehicle speed is greater than 40 MPH
3. Both conditions existing for a time greater than 25 seconds

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) Tests the power steering pressure switch for proper operation by using the self-diagnostic system. LO should be displayed when high power steering pressure loads are created.

Test Number 2) This step determines whether the fault is in the switch or the circuit. A jumpered switch connector should normally indicate HI if the circuit is complete. If so, the power steering pressure switch or connection is faulty.

Test Number 3) If display switches to HI when circuit No. 495 is grounded, the fault is an open in circuit No. 450.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Check for the following conditions

1. Poor Connection or Damaged Harness. Inspect ECM harness connectors for backed out terminal BD4, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
2. Intermittent Test. If connections and harness check okay, monitor EI78 display, while moving related connectors and wiring harness. If failure is induced, reading will change. This will help to isolate location of the malfunction.

Code E046: Circuit Diagram & Flow Chart PSPS Circuit. Scheme 190

CODE E047, ECM-BCM DATA

Check for momentary loss of BCM's 7 volts (circuit No. 807), ignition No. 3 (circuit No. 750) and PROM. See appropriate BCM charts.

If Code E047 is set along with any of the following codes set as HISTORY, B334, B335, B336, B337, B552 and B553, see chart on multiple intermittent codes.

CODE E048, MISFIRE DIAGNOSIS

Code E048 will set if following conditions are met

1. TPS is between .48 and 1.30 volts
2. RPM is between 1300 and 2100
3. MPH is between 50 and 60
4. Oxygen sensor cross counts are greater than 21
5. All of the above for 30 seconds

Code E048 will set when a problem exists with electrical system, fuel system or a basic engine problem, such as

1. A fuel related problem (such as restricted fuel injector).
2. A problem with ignition system such as bad plug wires, spark plugs or coil pack.
3. Check for other engine related problems such as burned or worn valves, weak valve springs, poor compression, worn camshaft or faulty lifters.

Code E048: Flow Chart Misfire Diagnosis. Scheme 191

CODE E051, MEM-CAL ERROR

Checks that all pins are fully inserted in socket. If okay, replace PROM, clear memory and recheck. If Code E051 reappears, replace ECM.

CODE E058, VATS SYSTEM FUEL ENABLE CIRCUIT

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) If vehicle will not crank with Code E058 stored, problem affects entire VATS system and is not isolated to fuel enable circuit. Refer to appropriate manual for VATS system diagnosis.

Test Number 2) ECM supplies battery voltage to circuit No. 229 which VATS decoder module pulses to ground when correct key resistance is recognized. Test ensures ECM is supplying battery voltage and circuit No. 229 is not open or shorted to ground.

Test Number 3) Checks PWM signal from VATS module. Since battery voltage supplied by ECM is pulsed to ground, voltage on circuit No. 229 should be around 6 volts.

Test Number 4) Checks for faulty ECM or intermittent condition by clearing Code E058. Since ECM ignores absence of fuel enable signal only when Code E058 is stored, vehicle should not start if problems present and Code E058 has been cleared.

Intermittent Code E058 and/or possible no start can be caused by the following conditions

1. A loose ground or poor ignition or battery connection could cause an intermittent loss of VATS fuel enable signal and Code E058 to be set.
2. Check for damage to harness which could cause an intermittent open or short to ground, backed out terminals at ECM and VATS decoder module connectors, broken locks, improperly formed or damaged terminals.

Code E058: Circuit Diagram & Flow Chart VATS System Fuel Enable Circuit. Scheme 192

CODES E063, E064 & E065, EGR FLOW CHECK

Codes E063, E064 and E065 are EGR flow test failures. The ECM, on a closed throttle coast down, will cycle solenoids on and off individually and look for a consequent change in engine RPM and O2 sensor activity.

Note. Test numbers refer to test numbers on diagnostic chart.

Test Number 1) If a code is set, inspect EGR for damage. Start and idle engine. Enter ECM overrides ES02, ES03 and ES04. You should be able to discern a change in engine RPM as the ECM turns on the EGR. Override ES02 should result in a small change and ES04 in a large change in RPM. The engine may stall when ES04 is turned on.

Note. If digital EGR valve shows signs of excessive heat, possibly slightly melted, check exhaust system for blockage (possibly a plugged converter). Refer to RESTRICTED EXHAUST in BASIC DIAGNOSTIC PROCEDURES article. If exhaust system is restricted, check for cause, one of which might be an injector which is open due to grounded driver circuit or faulty ECM. If this condition is found, oil should be checked for possible fuel contamination.

Code E063, E064 & E065: Circuit Diagram & Flow Chart EGR Flow Check. Scheme 193

See also:
• TESTS W/CODES - BCM
• DISPLAYING TROUBLE CODES
• TEST TYPE SELECTION
• ENTERING SELF-DIAGNOSTICS
• SYSTEM SELECTION
• EXPLANATION OF SPECIFIC TEST SELECTION
• MAKING SPECIFIC TEST SELECTION